Overbored Piston Weight

[Jim662]

I'm replacing one piston in my 1970 1150 (inline 6 cylinder). I went for a .015 over piston on cylinder 1 and the machine shop guy ordered me one from ProMarine.com. It is their part no. 9015. I read on this board that ProMarine's pistons are made by the same aftermarket manufacturer as Sierra and many others. This piston is made in Argentina. I initially thought it was a Wisco piston he bought, but Promarine claims they have their pistons made for them.

Well, it weighs almost ONE OUNCE more than my stock pistons.

This raises several questions:

1) I'm planning on going with another piston, probably Sierra. I'm hoping that what I read about the same manufacture doing both pistons is wrong. Does anyone know for sure. Has anyone ever weighed the aftermarket pistons they installed? What kind of variance are you seeing.

2) What is the acceptable weight difference between pistons. This one is something like 27 grams. That has to be too much. What is OK?

Thanks for the help,

Jim

 

[cell]

Re: Overbored Piston Weight

Seems like a lot.Tho I never rebuilt an outboard just some truck/car engines...but then again those engines don't spin at 6000 rpm.Couldn't you take a little of the skirt like a auto piston?I also read on here that replacement piston from mercury are pretty much on the spot with older pistons.